Demand for biodegradability and water dispersibility in disposable products is increasing rapidly with growing concern for the environment along with increasing consumer preference for products which are “flushable” so that they are convenient to dispose of and will not clog plumbing or foul septic equipment.
While low density polyurethane foams are known, these products are generally not water dispersible or soluble. Recent attempts have been made to produce soft and resilient polyurethane foams which are at least biodegradable so that they are more environmentally acceptable. For example, biodegradable starch based polyurethane foams are described by Kwon et al; however, these foams are clearly not water dispersible—as apparent from the reported absorbency results see Kwon; O-J.; Yang, S-R.; Kim, D-H.; Park, J-S. J. Appl. Polym. Sci. (2007), 103, 1544.
Conventional polyurethane foams used in cosmetic pads and other consumer products are typically neither water soluble nor biodegradable.
Foams made from starch and other water-soluble polymers, such as polyethylene glycols and polyvinyl alcohols and the like are sometimes reported to be water dispersible; however, these products do not generally have mechanical properties (softness and resilience) suitable for personal care products or sufficient resilience to be used as a substitute for conventional soft and resilient polyurethane foams used to package fragile electronic products. See Li, X. 2007033598/WO-A1 (Mar. 29, 2007). Moreover, starch based compositions tend to require high levels of plasticizers and the like for softness, are difficult to foam and so forth. See Griesbach, U.S. Pat. No. 5,506,277 (Apr. 9, 1996). Further information concerning foams generally with or without starch is found in the following U.S. Pat. Nos. 3,004,934 to Dosmann et al.; 3,137,592 to Protzman et al.; 3,165,508 to Otey et al.; 3,402,170 to Fuzesi et al.; 3,405,080 to Otey et al.; 4,863,655 to Lacourse et al; and 6,608,118 to Kosaka et al. as well as Ribble et. al., U.S. Patent Application Publication No. US2004/0048759 wherein a water dispersible foam cleansing bar is described.
It should be noted that starch foams generally, while soft in that they compress easily, also have a stiff hand when flattened out, which makes them ill-suited for foam applications where a soft, supple, resilient flexible hand is desirable such as in cosmetic pads and tissue-like products used for personal cleaning where stiffness of the product is particularly disliked by consumers.
This invention provides foams which are readily cold-water dispersible and have mechanical properties, that is, softness and resilience, suitable for disposable personal care products.